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2,5,6-Trichloro-3-formyl-1-(β-D-ribofuranosyl)indole (4.3, 171 mg, 0.45 mmol) was dissolved in isopropylamine (10 mL), and the resulting solution was stirred at room temperature for 16 h. The solvent was then evaporated and the residue dissolved in EtOAc (50 mL). The suspension was washed with H2O (20 mL) and brine (50 mL), then dried over MgSO4, filtered and evaporated to yield a yellow syrup. The residue was dissolved in MeOH (1 mL) and subjected to column chromatography (40×350 mm) on silica gel with 20% MeOH/CHCl3. Fractions containing product were pooled and evaporated to yield a clear viscous residue which was dissolved in MeOH (1 mL) and subjected to column chromatography (40×350 mm) on C18-reverse phase silica gel with 75% MeOH/H2O. Fractions containing product were pooled and evaporated to yield a white solid which was recrystallized from MeOH/H2O to yield 76 mg (42%) of 4.19 as a white microcrystalline solid: mp 143-145 C; Rf 0.6 (20% MeOH/CHCl3); 1H-NMR (500 MHz, DMSO-d6): δ 9.90 (s, 1H), 8.19 (s, 1H), 7.73 (s, 1H), 7.26 (d, 1H, D2O exch.), 5.87 (d, 1H, D2O exch.), 5.68 (s, 1H, D2O exch.), 5.37 (d, 1H, D2O exch.), 5.29 (d, 1H), 4.35 (q, 1H), 4.10 (s, 1H), 4.07 (m, 1H), 4.00 (s, 1H), 3.70 (m, 2H), 1.28 (s, 6H). 13C-NMR (125 MHz, DMSO-d6): δ 181.55, 153.38, 133.43, 127.15, 123.96, 122.70, 119.37, 111.47, 99.04, 88.51, 85.88, 70.76, 69.80, 60.69, 48.99, 22.77, 22.55. HRMS (ES) m/z calcd. for C17H20Cl2N2O5·Na·CH3OH 457.0909, found 457.0912. Anal calcd for C17H20Cl2N2O5·¼H2O: C, 49.53; H, 5.13; N, 6.80. Found: C, 49.83; H, 5.04; N, 6.51.
